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FC Taps and pressure

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BobbyBoucher

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Hi all,

I'm trying to work out the best use of the FC Perlick taps in my system. My problem at the moment is I'm getting excellent pours for the first half of my keg then progressively more foam the closer I get to the bottom. By the time I'm getting to the bottom quarter of the keg I'm getting lots of foam.

I know that different temperature has an effect on the carbonation and I know that in some kegerators there can be a big temp discrepancy between the top and and the bottom of the fridge. Most people fix this with a fan inside the fridge, I don't have room for one so this fix will not work. Is the purpose of the FC taps that I can run a higher pressure and have the FC turned down at the start of the keg and then turn it up towards the end? Or is it the other way around? Does this help me regulate the pour and therefore the foam?

Running the system at 12PSI with around 2.5m of line from keg to tap.

Cheers

Bobby Boucher
 

MHB

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The fan can be small, just one of the little computer fans from Jaycar or the like will do. You can even screw it to the top of the fridge or in a corner, basically anywhere that lets air in and out.
It really is the only fix.
Mark
 

BobbyBoucher

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So the issue is the difference in temp? Is that what is causing the change in pour?

If that is all it is it's incredible what an impact it has.
 

MHB

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Well its actually two main factors working together.
First is temperature, Its pretty easy to have 5oC or more difference in a fridge between the top and the bottom of a keg, given that solubility is dependent on temperature and pressure. At a fixed pressure in your case 12psi (wash out mouth) or ~83kPa, say you mid point temperature is 4oC and top and bottom were 6 and 2 respectively, you would have a dissolved CO2 content of ~4.6g/L and ~5.4g/L. might not sound like much but its 15% more dissolved CO2.

The other big one is the Area to Volume. Gas travels into (and out of) beer through the surface, in a keg you have the same area when the keg is full as when it is say 1/4 full. But you only have 1/4 as much beer to absorb the gas
and its colder so it will transfer faster and saturate sooner 4 times sooner.

Put the two together and yes without a fan in there the top half of the keg will be under-carbonated or the bottom half will be over-carbonated. Add in that the closer you get to the bottom the bigger a pita it becomes - fitting a fan starts looking like a really good idea.
Mark
 

JDW81

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Hey Bobby,

I can probably speak with some authority on this system ;), but first a couple of questions.

How are you carbonating your kegs, and how long is it taking to get the keg to half full?

This isn’t a problem I ever had, so I’ll give you a run down of how I went about it.

I had about 1-1.5m of beer line between the keg and the taps. I’d force carbonate using the rocking method, the let it sit for a minimum of 24 hours before turning on the gas at serving pressure (usually around 10-12 PSI), although have always wondered how accurate the regulator actually is.

I agree there isn’t room for a fan in there, and that you can get temp differential between the top/bottom of the keg.

I wonder if you’re getting a bit more carbonation from your set serving pressure which may contribute? Is it possible that you’re kegging prior to fermentation is complete and there’s a slow ferment happening in the keg while it’s in the fridge?

What you can do (which is the beauty of the FC taps), is if you find you’re getting a bit too much foam is to restrict the flow a bit more (push the little toggle at the back so it’s pointing down more) which should help. The other thing to make sure of is that the beer out disconnect isn’t getting clogged with hop matter. If you get hops stuck in there, it will cause foaming and no amount of trouble shooting will fix it until you clear them out of the post.

Send me a PM if you’re still having trouble, and I’ll see if I can help trouble shoot some more (would offer to come round a help out, but not in Geelong anymore so unfortunately won‘t be able to do it in person).

Good luck mate.

JD
 

JDW81

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I should add, I would often move the flow restrictor depending on how the beer was pouring throughout the keg (more of an issue in summer when the taps would get warm in the garage).
 
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I am running Intertap FC taps with 1.2 metre x 5mm I/D Eva Barrier beer lines in a series 4 kegerator. I also naturally condition my kegs, if I have any issues I just restrict the flow to suit the pour.
 

Lorenzo99

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My money is on hops blocking either the tap or the ball lock on the keg. I had the issue of beer pouring nothing but foam even with the tap set to just a trickle. This used to happen regularly with high amounts of dry hops. It would always happen early on for me though not towards the end of the keg. I used to rack to keg carb through a carb stone at 350kpa for 1 hr vent set to 85kpa and serve.
 

BobbyBoucher

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Hey Bobby,

I can probably speak with some authority on this system ;), but first a couple of questions.

How are you carbonating your kegs, and how long is it taking to get the keg to half full?

This isn’t a problem I ever had, so I’ll give you a run down of how I went about it.

I had about 1-1.5m of beer line between the keg and the taps. I’d force carbonate using the rocking method, the let it sit for a minimum of 24 hours before turning on the gas at serving pressure (usually around 10-12 PSI), although have always wondered how accurate the regulator actually is.

I agree there isn’t room for a fan in there, and that you can get temp differential between the top/bottom of the keg.

I wonder if you’re getting a bit more carbonation from your set serving pressure which may contribute? Is it possible that you’re kegging prior to fermentation is complete and there’s a slow ferment happening in the keg while it’s in the fridge?

What you can do (which is the beauty of the FC taps), is if you find you’re getting a bit too much foam is to restrict the flow a bit more (push the little toggle at the back so it’s pointing down more) which should help. The other thing to make sure of is that the beer out disconnect isn’t getting clogged with hop matter. If you get hops stuck in there, it will cause foaming and no amount of trouble shooting will fix it until you clear them out of the post.

Send me a PM if you’re still having trouble, and I’ll see if I can help trouble shoot some more (would offer to come round a help out, but not in Geelong anymore so unfortunately won‘t be able to do it in person).

Good luck mate.

JD
An absolute authority I'd say JD! Thanks for sharing your input.

I carbonated this keg with the set and forget method. 12 PSI (sorry MHB) and came back in 2 weeks, worked really well for this and the other kegs I have in there. I'll try and restrict the flow a bit more and see how it goes. I'm running a bit more line than you used to so I'll see how the other kegs behave when they get down low. Might be worth trimming one line to 1.5m and seeing how it effects performance. At a minimum it would certainly make the door easier to close with less line bunching up everywhere.
 

BobbyBoucher

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I am running Intertap FC taps with 1.2 metre x 5mm I/D Eva Barrier beer lines in a series 4 kegerator. I also naturally condition my kegs, if I have any issues I just restrict the flow to suit the pour.
I just started a natural carbonation on a keg yesterday so I'll see if this makes any difference.
 

BobbyBoucher

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Well its actually two main factors working together.
First is temperature, Its pretty easy to have 5oC or more difference in a fridge between the top and the bottom of a keg, given that solubility is dependent on temperature and pressure. At a fixed pressure in your case 12psi (wash out mouth) or ~83kPa, say you mid point temperature is 4oC and top and bottom were 6 and 2 respectively, you would have a dissolved CO2 content of ~4.6g/L and ~5.4g/L. might not sound like much but its 15% more dissolved CO2.

The other big one is the Area to Volume. Gas travels into (and out of) beer through the surface, in a keg you have the same area when the keg is full as when it is say 1/4 full. But you only have 1/4 as much beer to absorb the gas
and its colder so it will transfer faster and saturate sooner 4 times sooner.

Put the two together and yes without a fan in there the top half of the keg will be under-carbonated or the bottom half will be over-carbonated. Add in that the closer you get to the bottom the bigger a pita it becomes - fitting a fan starts looking like a really good idea.
Mark
Thanks for such a detailed answer Mark. If I'd known you were going to reply I might have referenced something other than PSI!
 

donald_trub

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I've never thought about the temp difference in my keg fridge. I have a font fan (Digital Homebrew) stuck to the ceiling of the 3 keg kegerator. Do you think leaving that running would be enough to even out the temp? The fan is sucking and blowing the air up the font and doesn't feel very strong, so not sure if I'd need to add another for ciculation.
 

MHB

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Thanks for such a detailed answer Mark. If I'd known you were going to reply I might have referenced something other than PSI!
It comes down to how you think about brewing. If you think its just some type of magic then it isn't important what you measure things in (or don't measure as the case might be).
If you understand that brewing is also a science and all the bits we measure are interrelated its very important that you work in units that allow interrelation, or its back to thinking brewing is all voodoo.
The equations that predict dissolved CO2 are based on pressure expressed in "Standard Atmospheres'" and temperature in oK (Kelvin where 0oC is 273.15oK). When you start working with the CO2 produced by fermentation and how that is used to carbonate packaged beer, you start needing to be looking at CO2 in terms of g/L.
If you do any brewmaths you will end up doing all the work in SI (~metric) then converting it into irrational units, apparently just because Americans do, which I find pretty hard to understand.
Mark

DT
Don't know
But if you measure the temperature top and bottom you should get an answer.
If its blowing up the font, leaving it running all the time could use up a fair amount of electricity, it might be better to put in a separate fan just for the fridge.
M
 

gaijin

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Just throwing this out there as well; I had a similar issue to BB.

I purchased a 20year old Simpson fridge which had a radiator plate (I think) at the rear of the fridge. Kegs that needed to be pushed up against it for space seemed to be giving me the foaming problems. I think that the kegs were thermally conducting the lower temps, icing up slightly and the ice crystals were blocking the outlet tube and causing serious turbulence and causing me severe mental anguish. Of course, Lorenzo might be right and it could be hop blockage also.

My solution was always to let the keg chill to room temp and defrost potential ice, purge CO2 and reconnect. I then placed an old car mat between the wall of the fridge and the kegs. The car mat has worked for me so far for future kegs and I haven't had to defrost any more.

One beer line of my two seems to give more head than others, but it no longer foams. I'm thinking it could be beer scale as I haven't caustic cleaned for a while - I'm doing this today.

Hope this helps - and thanks for the great advice all.
 

pat_00

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I have both a Perlick and an Intertap and have found they both need more line than what I was told. I used to have about 1.5m on both and would constantly have foaming issues. I just ran new lines, 4m each and now they work a lot better.
 

RRising

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I have both a Perlick and an Intertap and have found they both need more line than what I was told. I used to have about 1.5m on both and would constantly have foaming issues. I just ran new lines, 4m each and now they work a lot better.
What was the inner diameter of your line? iirc the larger the diameter the longer the line needs to be.
 

JDW81

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An absolute authority I'd say JD! Thanks for sharing your input.

I carbonated this keg with the set and forget method. 12 PSI (sorry MHB) and came back in 2 weeks, worked really well for this and the other kegs I have in there. I'll try and restrict the flow a bit more and see how it goes. I'm running a bit more line than you used to so I'll see how the other kegs behave when they get down low. Might be worth trimming one line to 1.5m and seeing how it effects performance. At a minimum it would certainly make the door easier to close with less line bunching up everywhere.
I reckon there’s potentially 2 things going on here.

The first is a bit of carbonation creep. You set and forget, and it’s all sweet but as time goes by the pressure continues to force CO2 into the beer and where you’ve got the flow restrictor set isn’t enough when you get a bit further into the keg.

The second is potentially due to the temp being colder at the bottom of the fridge than where the changes are in the door. As it’s colder down the bottom, there’s a bit more CO2 in solution and it comes out with the slightly higher temp up the top of the fridge and in the shanks.

You can either back off on your serving pressure once you’ve got the carbonation right, or just restrict the flow a little more to prevent foaming.

JD
 

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